Research has recently become increasing active in the area of intercellular networks, and proposals have been made for constructing intercellular networks in vitro. Cell networks that have been constructed in vitro are useful in imaging research and electrophysiological research using the patch-clamp method. In order to construct an intercellular network in vitro, it is necessary to culture cells arranged at prescribed locations. For example, in Non-Patent Document 1, an experiment was conducted to detect the electrical potential of nerve cells by providing a region surrounded by a plurality of projections on a silicon substrate having a transistor arranged thereon, and arranging peripheral nerve cells of Lymnaea stagnalis in the form of large ganglia thereon. In addition, Non-Patent Document 2 discloses a neurochip obtained by forming a plurality of roughly disk-shaped enclosures referred to as “cages” on a substrate, arranging nerve cells in a space in the center of the cages, and allowing axons of the nerve cells to extend through several tunnels provided in the cages towards nerve cells in adjacent cages. However, Non-Patent Documents 1 and 2 do not disclose nerve cell seeding systems for efficiently seeding nerve cells in a large number of cell establishment areas. Methods involving the manual seeding of cells in individual cell arrangement areas using equipment such as ordinary pipettes, pipettes equipped with a measuring function or micro-injectors make it difficult to accurately seed cells in extremely minute cell arrangement areas, thereby resulting in inferior seeding efficiency and making these methods undesirable.
On the other hand, the patch-clamp method is an electrophysiological technique for examining signal transduction between cells by measuring membrane potential and membrane current, and is carried out using ordinary pipettes. However, in the case of the pipette patch-clamp method, since the technique involves capturing (clamping) individual cells with a pipette followed by measuring their electrical changes, it is unable to accommodate high-throughput screening by multi-point measurement. The inventors of the present invention developed a planar patch-clamp method for the purpose of using the patch-clamp method for high-throughput screening (Patent Documents 1 and 2). This planar patch-clamp method consists of providing a plurality of microscopic through holes in an electrically insulated substrate and then measuring electrical changes, such as changes in membrane potential or membrane current, in cells arranged on these through holes, thereby enabling high-throughput screening by multi-point measurement. However, in order to construct an intercellular network in vitro, similar to the difficulty encountered in seeding cells into a large number of cell establishment areas, the difficulty remained in accurately arranging cells on a plurality of the through-holes in the electrically insulated substrate.
Thus, in order to construct an intercellular network in vitro, it is additionally required to be able to accurately and rapidly arrange cells in prescribed arrangement areas in order to study electrical properties using the planar patch-clamp method.
In addition to methods using pipettes, an automated cell seeding method that mechanically automates a cell seeding method using pipettes by utilizing the principle of an inkjet printer has been developed for use as a technology for seeding cells in prescribed cell arrangement areas (Patent Document 3). In addition, as another example of a technology for cell seeding, a technology has been implemented for seeding cells based on the principle of embedding cells in sequential cell arrangement areas in the form of depressions by transporting cells to a prescribed depression using microchannels and then transporting the cells to the next depression when that depression has been filled (Non-Patent Document 3).